Radio tuning apparatus



oct. 2s, 1941. H, z BENTONU I 2,260,599

RADIOTUNINQ APPARATUS Filed Aug. 15, 194 4 shets- ,et 1 .eQJr .yd

ocf. 2s, -194,1.I H z, BENTON TAL 2,260,599

RDIO4 TUNING APPARATUS Filpd Aug. 15, 1940 '4 Smets-sheet 2 Hama 2.1mm' and Lloyd l. Morris, INVENTORS:

-BY x M- H. Z. BENTON ETAL RADIOTUNING APPARATUS od. 2s, 1941,-

4 sheets-sheet 3 Filed Aug. 15, 1940 @hay v vil' Il Harald Zenafz and Lleyd l Marlis,

HJVENTORS:

AroRNEY.

H. z. BEN'ToN ETAL RADIO TUNING APPARATUS Filed Augf 15, 1940 Oct. 28, 1941. 2,260,599

4 Sheets-Sheet 4 2% 1,2%? l Zw g me w3 Z?? g l /MY 260264 72%? [zu Z "263 zff Il -Il l 74 261 2,21/ ,ef/03 eze' m 3.1K

e n 235 Z6 i 76 Harald Z and Llaydmhor,

Patented Oct. 28, 1941 2,260,599 RADIO TUNING APPARATUS Harold Z.

ration of Illinois Benton, Glencoe, Chicago, Ill., asslgnors to and Manufacturing Co.,

and Lloyd P. Morris, Crowe Name Plate Chicago, Ill., a corpo- Application August 15, 1940, Serial No. 352,692 s claims, (c1. n n) This invention relates to a new and improved radio control device and more particularly to de`- While our control device is especially adapted for push button operation, it is capable of continuous manual operation for tuning throughout its range. The invention further relates-to details of construction of push buttons and their adjustment mechanism and to means for connecting the movable tuning parts to movable tuning elements of the radio circuit.

The present trend in radio tuner design is to provide means for continuously tuning the radio receiver and also means, such as push buttons, for rapid and accurate tuning of selected stations. A large proportion of commercially produced receivers are now made in small and com pact sizes which requires that the tuning devices and the elements of the tuned circuits be reduced in size.

The tuning of circuits requires a change in the inductance or capacity in the circuit, the usual method being means of variation in capacity connected in parallel to an inductance. Such capacity variation is caused by rotary variable condensers, the sizes of which are such that they occupy the major portion of the space occupied by the tuning elements. The method of permeability tuning by the use of small cores movable relative to the coils affords a more compact tuning element than a variable condenser and coils, and this is especially true when the circuit tuning elements are directly and closely assembled with the mechanical tuning members such as the push buttons and dials.

Permeability tuning can be accomplished over the usual broadcast band by relatively short movement of a core of suitable effective permeability associated with a small solenoid coil. Since a slight movement of the core makes a substantial change in the frequency response of the tuned circuit, it is essential that the core movement be always exactly uniform for a given dial or push button setting which requires that play and backlash in the connected operating elements be substantially eliminated.

It is an object of the present invention to provide a new and improved radio control device of the character including push button operation and permeability tuning of the radio circuits.

It is a further object to provide constructions of this character in which the push button ada change in effective tuning byA paratus composed of justment may be readily made from the front oi the unit without the use of additional tools.

It'is also an object to provide constructions with simple and compact mechanism for translating rotary action of a tuning member to linear movement of the movable core with the elimination of backlash or play between the parts.

It is an additional object to provide tuning apbut few parts and adapted for commercial production and use.

Other andy further objects will appear as the description proceeds.

We have shown certain preferred embodiments of our invention in the accompanying drawings, in which- Figure 1 is a side elevation, partly in section,l

of one form of push button tuning apparatus;

Figure 2 is a plan view, partly in section and partly broken away, of the construction shown in Figure 1;

Figure 3 is a fragmentary plan view, partly in section and partly broken away, of the latching mechanism of the construction shown in Figure 1;

Figure 4 is a fragmentary section on an enlarged scale, taken on line 4-4 of Figure 1;

Figure 5 is a fragmentary section on an enlarged scale taken on line 5--5 of Figure l;

Figure 6 is a fragmentary side elevation, partly in section of a construction similar to Figure 1 but showing a modified form of latch means for the push button slides;

Figure 'l is an elevation similar to Figure 1 showing a construction with a drum for manual operation and a brake for the dial and drum;

Figure 8 is a fragmentary front elevation of the construction of Figure'l;

Figure 9 is a fragmentary plan view showing a release for the flapper bar spring;

Figure 10 is a fragmentary plan view showing a construction of flapper bar brake;

Figure ll is a view similar to Figure 10 but showing a different form of construction;

Figure 12 is a fragmentary view on an enlarged scale showing the form of connection between the apper bar and core used in the forms of construction shown in Figures l to 8, inclusive;

Figure 13 is a fragmentary side elevation of a modified form of connection between a moving bar and core;

Figure 14 is a View Figure 13;

Figure l5 is a View similar to Figure 13 but showing a modified form of construction;

Figure 16 is a fragmentary view showing antaken on line I4l4 of other form of connection between a core and core moving means;

Figure 17 is .a fragmentary elevation showing a form of connection between a core pull rod and core moving means;

Figure 18 is a fragmentary plan view showing a connection between a core pull rod and driving means;

Figure 19 is a fragmentary side view of this same form of connection between a core pull rod and core swinging arm;

Figure 20 is a fragmentary side elevation showis provided with an inwardly extending arm 45. This arm 45 is connected by link 40 to an arm 41 extending from the dapper bar 26.

As best shown in Figure 3, the cross frame member 2| carries the sliding latch bar 4l held in place by clips 49 and normally drawn against the slidesvby the coil tensionspring 49a. The latch bar 43 is -provided wlthopening's through which the slides 23 pass. Each slide 28 is provided with two struckup projections, these being the release cam 50 and the stop 5|. The release ing a coil and core supporting and moving construction;

Figure 21 is a side elevation, partly in section, showing a form of push button tuner; and

Figure 22 is a view similar to Figure 21 showing a modified form of construction.

Referring first to the form of construction shown in Figures 1 to 5, inclusive, the tuner is provided with a frame 20 having a front vertical flange 2|, an intermediate vertical guide flange 22, and a rear flange 23. The frame is also provided with side flanges 24 and 254. 'Ihe swinging fiapper bar 26 is pivotally supported in the side flanges 24 and 25 at 26. Its lower portion is connected to flange 22 by the spring 21 which tends to swing the bar in the countercloclwise direction as seen in Figure 1. The push button slides 28 are guided in the front flange 2| and have reduced portions 29 passing through narrow slots 30 in the bar 26. They are further provided with narrow inner end portions 3| guided in slots in the intermediate cross frame member 22.

Each slide the narrower portion 3| of the slide. One end of this spring presses against the front face of the intermediate frame member 22, while the other end of the spring presses against the shoulder 33 between slide portions 29 and 3|. spring, therefore, normally keeps the push button slides at their outer limit of movement or to the left as shown in Figures 1 and 2. Movement in this direction is limited by the lugs 34 which engage the inner face ofthe front frame flange 2| ach slide 28 is provided with a struckup portion 35 extending laterally at right angles to the body'of the slide, this portion 35 having a thread ed opening to receive the plunger screw 33. This screw 3B is provided with a narrow flattened adjusting end 31 and with a rounded inner end 38 adapted to engage the face of the flapper bar 26 at one side of the slct 30 through which the slide passes. The slide 28 is further provided with an outer face member 28 bent at right'angles to the body of the slide, parallel to the struckup portion 35. 'I'his member 28' is square in shape and is provided with a guide opening through which the screw 36 passes. The hollow push buttons 35 fitted ori-the slide portions 38, are provided adjacent their open end with a. plurality of pairs of flanges 40, as shown, in detail in Figures 4 and 5. These flanges are of such depth as to extend closely 'adjacent the surface of the screw 36, and each pair is spaced apart a distance sufficient to permit the flattened portion 31 of the screw 36 to pass or fit between them, as shown in Figure 4.

The drum dial 4| is carried in arms'extendingv upwardly from the side flanges 24 and 25 of the frame and its shaft 4| is provided at one end with a small gear 42 which meshes with the gear sector 43. This gear sector 43 is pivotally supported at 44 on the side 28 has a coil spring 32 fitted about This frame member 24 andL with insulating bases cam 5l is higher than the stop 5| and will thus slide the latch bar sufficiently to fully release the stop 5| of another bar as the slide is pushed in. The release takes place early in the travel of the slide so that the released slide comes out in ample time to permit the latching of the slide being pushed in. 'I'he stop 5| has a square front face 52 to engage the latch while the cam 50 is rounded at both ends and the slide spring 32 is sufficiently stronger than the latch spring 49a so that the slide cornes out quickly when thestop 5| is released.

The tubular coil forms 6| and 62 are provided 63 and 34 which are held against the rear transverse frame member 23 by clips i5. These coil forms 6| and 62 carry the coils 56 and 61. Into'the coil forms 6| and 62 are fitted the cylindrical cores 68 and 69, these cores being adapted to freely slide back and forth within the coil forms. Each core is provided with a connecting lug 10 having an opening therein,

l the opening being non-circular in shape with a pointed section extending" toward the core. As shown in detail in Figure 12, the push rod 1| is provided with a reversely bent curved end 12 passed through the opening in the connecting lug 10 and seating in the pointed section of the opening in the lug 10 adjacent the core. The opposite end 13 of the push rod 1| extends through an opening in the upper portion of the napper bar 26 and hasa bent portion thrusting against the flapper bar. The tension coil spring 14 is fitted around the push rod 1|, one end of it being hooked through the opening in the flapper bar 28 and the other fitting in the opening in lug 10 on the core. This coil spring, therefore, serves to take up any backlash in the connection between the flapper bar and core during the operation of the apparatus.

In order that the tuning apparatus may be manually tuned over the broadcast band or over the tuning band covered by means of the particular coils and cores provided, one push button is constructed for such tuning. The upper button 15 of Figure 2 is constructed for this purpose. The button has continuous interior guides 18 for engaging the flattened portion 31 of the associated screw 3B. 'I'he transverse end 11 of' slide 13 is circular in shape so that the button 15 may be rotated without withdrawing it from the slide. The slide 13 is otherwise the same as slides 23. In the use of the button 'l5 for manual tuning, it is pushed in and latched in in the usual manner. 'I'he drum dial 4| will show the tuning adiustment at which the button was left when last used. Rotating the button 15 moves the screw 33 in or out and thus moves the bar 26 and tunes the set, the movement being shown by corresponding movement of the drum dial.

It is to be understood that the cores 68 and 69 may be finely divided bility inductive 'tuning is used, or brass or other similar metal if variable high frequency coaxial inductive tuning is desired. If tubular capacitive powdered iron, if permea' .gear sector 43 and dial gear 42. if means were not provided to counteract the tuning is used the cores will be metal and will slide within the shells 8| and 82, being insulated therefrom, the shells being o! a metallic conductor and co-operative with the cores in such manner that the capacity between the movable cores and outside metal forms 8| and 82 will vary as the cores are moved within the hollow metal forms 8| and 82.y

A modified form of latch construction for the push button slides has been shown invFigure 6. The slide 80 is similar to the slide 28 of Figures 1 to 3, but is provided with a different form of narrow rear extension 8| having a notch 82 and a downwardly extending rear end 83. The cross frame member 22 is provided with rearwardly extending side arms 84 between which is pivoted a swinging latch -bar 85. The latch bar has an intermediate hump 88 and upturned end 81. The at spring 88 is supported by a stud 88 from the frame member 22, and engages the rearward face of the upwardly extending portion of the latch bar 85 as shown in Fig. 6. The parts are proportioned so that the hump 88 of the latch bar will pass freely under the reduced rear portion 8| of the slide, but will be engaged by the downwardly extending end 83 of the slide. The spring 88 serves to normally urge the latch bar in the counterclockwise direction.

The construction operates by pushing in any push button, this serving 85 in the clockwise direction due to the engagement of the slide end portion 83 with the hump 88 of the latch bar. This forces the upturned end 81 of the latch bar out of the notch 82 in the slide previously pushed in, which was held in the inner position by the latch bar. As the downwardly extending end 83 passes over the hump 88 of the latch bar, the bar swings upwardly so that after the upturned end 81 passes under the downwardly extending portion 83 of the latch bar it catches in the notch 82 to latch this slide in the operative position. f

The form of construction shown in Figure 7 is generally similar 5, inclusive, with to that shown in Figures 1 to the exception that instead of manually turning the device by means of one ol. the push buttons it is manually tuned by means of the knurled hand wheel 9|, which is securedl to the drum dial shaft 4|. The spring 21 connecting the frame portion 22 and the lower portion of the paddle bar 28 tends to urge the drum to its counterclockwise limit of movement through means of the arm 41, link 48, arm 45, Consequently,

21, the device could be manuholding the dial in the desired eiiect of the spring ally tuned only by position.

The slide 82 is generally similar to the slides 28 previously described, with the exception that it has an extended inner end 93, The brake cable 94 passes through an opening 95 in this slide extension 93 and passes around the drum 4|, as

shown in Figures 1 and 8. The tension spring 88 is connected in the cable 94 so that a positive tension is imparted to the cable 94. With the push button slide 82 in its outer position, this tension of the spring 98 and the braking effect of cable 84 'are not sufficient to overcome the normal movement fluence of the spring 21. When slide 92 is pushed inwardly, however, and latched in its inner position, the spring 98 is stretched and its tension increased sufficiently so that it overcomes the tendency of the spring 21 to move the drum in to swing the latch bar drum to remain fil) to the broken line position, the

the counterclockwise direction and causes the in any position to which it may be manually moved by means of wheel 8|. It will be understood that this does not necessarily make the wheel 8| hard to turn, as the braking etlect need not be excessively great after counterbalancing the spring 21.

A different means for releasing the tension of the paddle bar spring is shown in Figure 9. Here the paddle bar |0| is pivoted in the frame |02 and its lower edge is provided with the spring |03 which is similar in effect to the spring 21 of the constructions previously described. The opposite end of this spring, however, instead of being connected to the frame member |04, passes through that frame member and is connected to an upturned lug |05 carried by the bell crank member |08. This bell crank is pivoted in the frame at |01 and has a lever |08 for manual operation extending through the forward face of the frame. With the parts in the full line position shown in Figure 9, with lever |08 retained by latch |02a the spring |03 will be put under tension, While if the bell crank is moved tension on the spring will be released and the dial and tuning apparatus may be manually rotated to the desired position and will remain in that position without any action by spring |03.

A further modied form of brake for permitting manual adjustment of the dial and tuning mechanism is shown in Figure l0. In this construction the paddle bar is supported in the frame ||2 and carries on its shaft ||3 a cup ||4 having a lining ||5 of friction material, such as cork. The resilient brake member ||8 is pivotally supported at ||1 upon a rear extension of the frame ||2. This brake member ||8 is provided with an operating extension ||8 extending around to the rear of the frame |l2. button slide ||9 is carired in the frame ||2, the screw |20 being so short that it will at no time interfere with the movement oi the paddle bar This slide ||9 has a rear extension |2| which, when the push button slide ||8 is pushed inwardly and latched in its inner position, serves to thrust positively against the extension ||8 on the brake member I6, thus forcing that member firmly against the braking surface ||5 on the paddle bar. This braking eiiect can be adequate to overcome the force of the spring |22, which normally swings the paddle bar in the counterclockwise direction. It will be understood that the push button |23 on slide ||9 will be designated manual tuning,.and pushing this button in Will both release any push button previously pushed in and apply the brake as described above. When it is desired to go back to push button tuning, pressure on any other button will release the manual tuning button and tune the device in the usual manner.

Figure 11 shows a different type of construction for applying a brake to the swinging paddle bar so as to permitcontinuous manual tuning without interference from the spring normally swinging the bar against the push button screws. The paddle bar is pivoted in the frame |3| at |32 and is provided with the cup-shaped member |33 carrying the friction brake disc |34. The brake member |35 is pivoted at |38 on lug |31 extending from the frame |3|. The push button slide |38 passes through the front frame member |39 and through latch bar |44 which is connected to operate the brake |35 when the cam point |42 on the push button-slide travels inwardly to per- A push mit shifting of the latch bar by spring |46. The adjustable screw |40 is short so as not to engage the bar |30. The slide |38 is provided with the latch cam |4|, the high point |42 'of which serves to unlatch any slide being held in. The front end |43 of the slide serves to latch this slide in.

The latch slide |44 is movable against the inner face of frame'member |39 and is provided with an opening through which passes the rediced end |45 of the brake member |35. The spring |46 extends around the pivot |36 of brake member i 35, one end being hooked under the reduced portion |45 of the brake member and the other end being hooked around the lug |31. This spring tends to slide the latch bar |45 upwardly, as seen in Figure ll, and also tends to swing the brake surface |41 carried by brake member |35 against the brake disc |34. The .spring |48 tends to swing the upper edge of bar |30 to the left, as seen in Figure 11.

A push button slide |49 is shown adjacent the slide |38, this slide being similar to slide |38, with the exception that a latch slide stop lug |50 is provided at the end of the struckup cam |i. This stop lug |50 prevents the latch slide from moving far enough to apply the brake vlien tuning push button slide |49 is latched in.

In Figures 13 and 14 is shown a modified form of connection between the apper bar and the pull rods connected to the cores. In these iigures the iiapper bar |60 is pivoted at i 6| and is provided with upwardly extending portions |62 which are reversely bent at |63 to support a cross bar |64. As shown in Figure 14, the cross bar |64 is provided with the downturned end |65 to limit longitudinal movement. The coil support |66 carries the coil |61 and the cylin drical core |68 is slidable within the member |66. The flexible and resilient pull rod |69 has one end molded in the core or otherwise positively and permanently connected thereto. The connecting member is soldered, brazed or welded permanently to the bar |64. The free end |1| of the pull rod secured to the member |10 in the parts. The apper bar struckup portions .|12 which ceive and retain the spring |13, the upper'portion of which bears against the cross bar |64, thus preventing any play between this bar and its support at |63.

In Figures to 22, inclusive, various specific forms of means for connecting a movable core and core drive means are shown. In the form of construction shown in Figure 15, the iiapper bar or other swinging member |80 is pivoted on an axis at |8|. The tubular coil form |82 carries a coil |83, and a core |84 nts within the form |82 in such manner as to slide freely therein. The flexible resilient wire |85 has one end molded in the core |84 or otherwise positively connected to the core. Its free end |86 is soldered or welded or otherwise rigidly secured to the portion |81 of the movable member |80. This connection absolutely prevents any backlash or looseness between the driving elements and the driven core. It will be understood that the wire or similar member |85, which may be formed of steel, brass or bronze, is exible and resilient so that it does. not become bent or take any permanent set during operation.

In the form of construction shown in Figure the 'assembly of.

are adapted to -re- 16, the core has an eye 202 molded or otherwise permanently and xedly secured to the core.

i 69 is soldered or otherwise- |60' is provided with;

the core 2|0 has a The pull rod 203 has a hooked portion 204 passed through an opening in the eye 202. The compression coil spring 206 has one end bearing against the face of the core 20| adjacent the eye 202. The opposite end of the coil spring is reduced in diameter and engages deformed portions 206 formed in the pull rod 203. The spring, therefore, presses against the core and the pull rod and eliminates all play or looseness in the connection between the pull rod 203 and the eye 202.

In the form of construction shown in Figure l pull rod 2|| molded or other` Wise fixedly secured therein. This pull rod 2li is provided right angles to the body of the pull rod and fitting in an opening 2 |3 formed in the fiat drive arm 2| 4. This opening 2 i3 has arlower V-shaped portion 2|5. The drive arm 2|4 is provided with a pin or stud 2|6 about which is fitted one end of the coil spring 2|1. The opposite end of this spring is hooked around the portion 2|2 of the pull rod 2H, holding that portion down in the V-notch in the lower portion of the opening 2|3. This spring connection, therefore, prevents play or looseness between the parts.

In the form of construction shown in Figures 18, 19, the pull rod 22| has one end molded or otherwise xedly secured to the core 222. 'I'his rod 22| has a transversely extending portion223 and a reversely bent portion 224. The driving member 225 is provided with an opening through which the transverse portion 223 of the pull rod passes. The member 225 also has an upturned end portion 226. The coil spring 221 is fitted around the extended portion 228, of the member 225 beyond the cross portion 223 of the pull rod, one'end of it engaging this portion of the pull rod and the other end engaging the portion 226 of the member 225. This spring serves to hold the parts in relativdy rlxed position and eliminates play or backwash at this point.

In the form of construction shown in Figure 20, 'the supporting frame member 24| has pivoted thereto at 242 a bracket 243. This swinging bracket has an outturned portion 244 to which is secured a base 245 carrying a coil form 246 upon which is Wound a coil 241. 'Ihe core 248 is slidably tted in the coil form 246 and this core has a rigid pull rod 248 molded therein or other- Wise rigidly and permanently and limit relative The intermediate the -nut 252 and engagement with the face of the bar 250 so that relative movement of the part is maintained In the form uniform.

26| and a These members to receive the These slides 263 pivoted thereto at 266.

with an end portion 2|2 turned at screw 210. This screw extends through a threaded opening in the clamping member 268 and its end engages the clamping member 261, thus forcing it against the face of the cam 264. The outer end of the slide carries the push button 21|. The swinging paddle bar 212 is pivoted at 212 in the frame 260 and is provided with slots 213 through which the reduced portions 214 of the slides 263 pass. The slides carry the coil springs 215, one end of each spring engaging the cross frame4 member 26| and the other end engaging the shoulder 216 on the slide. These springs normally maintain the slides at their outer limit of movement and return them to that position when pressure -is removed from the push buttons. The paddle bar 212 has a core drive arm 211 secured thereto, this arm, as shown, being formed of a flat member having its upper portion 218 twisted at right angles to its lower portion which fits against the face of the paddle bar. The portion 218 is provided with a notched slot 219 to receive the end of the connecting wire or pull rod 280, which end is turned at right anglesl to the body of the wire. The wire 280 is positively connected to the core 28| fitting in the coil form 282. This coil form carries the coil 283 and is supported from the rear transverse member 26| by the rearwardly extending bracket 284. The paddle bar 212 is provided with the hand wheel 285 for continuous manual tuning.

The form of construction shown in Figure 22 comprises the frame member 290, the push button slides 29|, and paddle bar 292 'pivoted at 292. The slides 29| are similar in construction to the slides 263 shown not be described in further detail. The side brackets 293 are secured to the sides of the frame 290 and are provided with openings 294 into which t lugs on the ends of a swinging support 295. This .swinging support carries a base 296 to which is connected the coil form 291. The core 298 is slidably fitted in the coil form 291 and is provided with a flat connecting lug 299. This lug 299 has a non-circular opening formed therein with a V-notch 300 located approximately in line with the line of thrust of the connecting arm 30|. This arm 39| has a reversely bent portion 302 secured to the paddle bar 292 so that the arm swings with movement of the paddle bar. It has a nger 303 extending through the opening inthe lug 299 and tting in the notch 300. with a hooked portion or is fitted one end of the coil spring 305. The other end of the coil spring is tted about a lug 306 extending downwardly from the member 30|. This coil spring serves to keep the nger 303 positively seated in the notch 300 and therefore eliminates play or looseness between the parts as the core is moved into and out of the coil upon rotary movement of the paddle bar 292.

In the use of the form of construction shown in Figures 1 to 5, in order to set up a push button for a desired sta-tion the selected push button is pushed in until the end 52 of the stop engages the inner face of the latch slide 48. The rounded end 38 of the screw 36 will engage the front face of the ilapper bar 26 and move that bar to an angular position, dependent on the adjustment of the screw 36 at the time.

It being assumed that this is not the desired adjustment, the hollow push button member 39 is withdrawn from the end of the slide to a pohorn 304 over which in Figure 21, and need' sition where the flattened end 31 of screw 36 fits between opposed pairs of flanges 40, as shown in Figure 4. The member 39 is then rotated and serves as a handle for rotation of the screw 36. Rotation of this screw 36 moves its inner end 38 inwardly or outwardly, depending upon the direction of rotation of the screw. The screw is rotated until the desired station is tuned in, it being apparent that this movement of the screw varies the angle of the flapper bar 26 and consequently moves the cores 68 and 69 inwardly or outwardly of their associated coils, depend- 'I ing upon the direction of movement.

I guide flanges 40 engage cated between theiianges 40.

The lug 299 is provided The indications on the dial drum 4| are of as`- sistance inl making this adjustment since the dial moves with movement of the apper bar 26, and it will therefore be readily apparent tothe person'setting up the push button as to which direction the tuning of the push button is going and the desired station can be identiiied by the indications on the dial. The exact tuning can then be accomplished by slight movement of the screw 36. v

After the desired adjustment is obtained, the hollow push button member 39 is slipped back to its position, as shown in Figure 1, fitting ilrmly on the squared portion 28 of the slide. The

the screw 36 and maintain the push button in proper alignment. It will be noted that at this time the flattened adjusting end 31 of the screw need not be in either a vertical or horizontal position as itis not lo- Other push buttons may be set up in the same manner. It will be noted that as a push button is forced inwardly or to the right as seen in Figure l, the cam 50 engages the latch bar 48 and slides it laterally. This movement of the latch bar releases its engagement with the stop 52 of whatever push button slide has previously been forced inwardly. The previously used push button is thereupon released early in the travel of the push button being tuned and does not in any way interfere with the latching of the subsequently used push button slide.

It will be apparent that during the push button operation of the device the push buttonv for the particular station being heard remains latched in its inner position. This gives an indication of the station being heard which, however, can also be ascertained by looking at the dial. If it is desired to tune continuously, itis necessary to release any push button slide which is latched in place. This, is accomplished by pushing in button 15, as shown in Figure 2, and when this button is latched in the inner position the latch bar is moved as desired by rotating the button, the movement of the dial 4| serving to indicate the tuning adjustment.

The form of connection between the flapper bar 26 and the core 68 shown in Figures l, 2 and 12 is efiicient in preventing backlash or play between the parts, which is essential in this type of tuner. It will be understood, however, that any one of the various other forms of construction for making an efiicient connection between such parts, which constructions are shown in the other figures of the drawing, may be incorporated in this type of push button tuner.

The method of assembly and operation of the different forms of connection shown in Figures 13 to 19, inclusive, are believed apparent fromthe drawings and the previous description of these types of construction.

In the form of construction shown in Figure 20, a rigid core pull rod 249 is used and the coil is permitted to have a rocking motion so as to prevent binding between `the core and the coil form. Tilting of the coil will take place as the ilapper bar 250 is swung back and forth, thus raising and lowering the free end of the pull rod 249.

In the form of construction shown in Figure 21, the push buttons are adjusted in the wellknown manner by releasing the clamping action against the cam 204. This is accomplished by turning the screw 210 so as to release the thrust against the clamping member 241. The screw 210 is always located in substantially the same linear position when in clamping action, and its head therefore may be rigidly and permanently secured to the push button 21|. Rotation of this push button serves to loosen and tighten the clamping action. The station is set-up by loosening the clamping action. thrusting the push button into its limit o1' movement so that the cam 264 engages the paddle bar 212, and then swinging the paddle bar to such a position as to tune in the desired station. With the parts in this position the cam 264 by screwing inwardly the screw 210. The push button may then be released and when thereafter pushed inwardly will always swing the paddle bar to the same position. It will be understood that in this form of construction the support of the paddle bar must have sumcient frictional drag so that it is held in adjustedpo;- sition. The paddle bar may be manually tuned by means of the hand wheel 205. The connection between the drive arm 211 and the core pull rod 280 is adjustable and the core may begiven a greater or lesser movement, depending on the length of lever arm utilized. It will be understood, however, that this adjustment will normally be made at the factory and will not thereafter be varied.

The form of construction shown in Figure 22 is adjusted in the same manner for setting up push buttons as has been described in connection with Figure 21. Here again the paddle bar 292 must be frictionally held so that it is maintained in adjusted position by friction regardless of any thrust upon it due to the weight oi the core and coil, which thrust is transmitted through the arm 30|. The paddle bar may be manually tuned by means of the hand w'heel 301. The spring 305 serves to prevent any play or backlash between the parts and when once adjusted the parts will always be returned to the same position upon the same movement of the paddle bar 292.

It will be understood that in both oi' the constructions of Figures 2l and 22 a dial may be connected to the paddle bars 212 and 292, respectively, in any desired manner, such, for example, as the manner of dial connection used in the form of construction of Figure 1. It will thus be possible to tune these constructions manually by their hand wheels.

While the form of construction shown in Figure 22 may be used in the position in which it is shown with the push buttons extending through the front of a cabinet. it is particularly is clamped and held adapted for use with thepush buttons projecting upwardly through the top of the cabinet in which case the core and coil are approximately horizontal. In this case the coils and cores may be located below the chassis, if desired. With units such as those of Figures 21 and 22 where the push button slides or screws do not remain latched against the bars, it is necessary to provide sumcient frictional or spring resistance to counterbalance any connected weight of coils and cores so that the movable bar will remain in any position to which it may be moved.

While we have shown certain preferred embodiments of our invention, it is capable of further change and variation to meet differing conditions and requirements and we contemplate such modifications as corne within the spirit and scope of the appended claims. And while particularly adapted for and shown in conjunction with permeability tuning, it will be clear that the invention is adapted as well to other forms of tuning, such for example, as capacity and coaxial capacity'tuning.

What is claimedis:

l. Radio tuning apparatus comprising a frame, a swinging bar pivoted in the frame, means normally swinging the bar in one direction, a plurality of means for selectively swinging the bar in the opposite direction, -a tuner comprising fixed and movable members, means connecting the movable tuner member to the swinging bar, a rotary dial mechanism, and means connecting the swinging bar to the dial mechanism, said means comprising a gear on the rotary dial, a gear sector pivoted on the frame and meshing with the dial gear and a link-connecting the swinging bar and the gear sector to rotate the sector/upon swinging movement of the bar.

2. Apparatus ior radio tuning, comprising a plurality of separately operable tuning slides, a pivotally mounted spring biased pivoted bar having openings therethrough for passage of said tuning slides, adjustable abutment screws on said tuning slides engageable with said pivoted bar at the sides of said openings therethrough for displacing said pivoted bar to the extent determined by the adjustment oi' said screws, a latch bar slidable over said tuning slides substantially at right angles thereto and provided with locking shoulders at the side of said tuning slides for holding the latter in advanced positions and tuning slide locking and releasing lugs in difierent positions on the sides of said tuning slides for operative coaction` with said locking shoulders.

3.,In apparatus for radio tuning, the combination with separately operable tuning slides, a latch bar slidably mounted for movement across said tuning slides substantially at right angles thereto and provided'with shoulders adjacent the diierent tuning slides for holding a slide which has been advanced in the advanced position and tuning slide locking and releasing lugs in diil'erent positions on said tuning slides for operative coaction with said locking shoulders on said slidable latch bar.

HAROLD Z. BENTON.

LLOYD P. MORRIS. 

